Nice game
This is a really nice game! I like the way it is not too difficult.
I found a bug: Sometimes, if the ball gets out of the boundaries of the game, it is impossible to return to the place where you started. For example, in the very large level, if you fall through the middle of the left boundary, you cannot bring it back and must refresh.
The hidden tunnel was a nice touch, but I think it would be best if you made the ball smaller and jump higher; it was odd that the stalagmites could only hurt the ball if it penetrated through the ball's centre.
This is overall a very good game and I hope you make more of these in the future!